Beacon vs Probe Response frame
| No | Beacon | Probe Response |
| Differences | ||
| 1. | It is always Broadcast. | It is always unicast. |
| 2. | Its Duration field is 0 because of point 1. | It has some value in duration field because of point 1. |
| 3. | It has TIM field which includes DTIM. | It does not have TIM field. |
| Similarities | ||
| 1. | Both frame types are management frame. | |
| 2. | Both have timestamp and Beacon interval field. | |
| 3. | Both have same capabilities information field. | |
| 4. | Both have same SSID field, Supported rate and WMM field. | |
| 5. | Both have ERP filed but Wi-Fi STA follows the ERP from Beacon frame for this. | |
| 6. | Both have HT information subset for HT protection but Wi-Fi STA follows the ERP from Beacon frame for this. |
If you have more important points for this post. Please let me know in comment section.
Anamika Raj
why is beacon required when probe response is already there? Can beacon frame be replaced with probe response?
Bamdeb
Hi Anamika Raj,
Thanks for reading the post.
Here are the some reason why do you need Beacon frame
1-> Beacon frame is an Broadcast frame and it’s like AP is advertising its own capabilities.
So it is easy to see AP’s capabilities by STA by doing only Passive Scan. STA does not have to send any frame to get AP’s information. Battery is saved for STA. Example: Your Android Phone WiFi scan uses Passive scan sometimes.
You can see active and passive scan in details in another post.
2-> Check point number 3 from post. Beacon frame carries buffered data information for connected STA in TIM or multicast data in DTIM. This is not possible in probe response frames it is unicast.
3-> All connected STA get time synced with Beacon as it comes as broadcast.
4-> Powersave STA can wake up in listen interval or any other time to check beacon if there is any buffer data. With probe response it’s possible.
5-> Again , as Beacon is broadcast frame , you can see Ap’s details in sniffer easily without depending on any probe response. Because to get probe response at least one STA has to send probe request.
These are the common reason i got , You can think many other reason easily.
Thanks
Bamdeb